1. Chapter 18: The Endocrine System
BIO 211 Lab
Instructor: Dr. Gollwitzer

2. Today in class we will: Discuss the hypophyseal portal system
Describe the endocrine system
Identify the organs and tissues of the endocrine system and the locations, associated structures, hormones and the functions of those hormones secreted by each of those endocrine organs, :
Pineal gland
Hypothalamus
Pituitary gland
Thyroid gland
Parathyroid glands
Discuss the hypophyseal portal system

3. Endocrine System
One of the body’s two coordination/communication systems
Nervous system is the other
Endocrine glands are ductless glands
Communicate with other cells/organs/ systems through release of hormones
Endocrine cells  hormone (chemical messenger)  interstitial fluid or circulatory system  target cells  effect(s)

4. Figure 1–2

5. Figure 1–2

6. Endocrine Organs Pineal gland Hypothalamus Pituitary gland
Thyroid gland
Parathyroid glands
Adrenal glands
Pancreas
Kidneys
Reproductive organs (gonads and placenta)
Other: heart, thymus, adipose tissue

7. Fig 18-1

8. Pineal Gland Location Contains Pinealocytes  melatonin
In posterior roof of third ventricle (epithalamus)
Contains
Neurons
Neuroglia
Pinealocytes (special neurosecretory cells)
Pinealocytes  melatonin

9. Pineal Gland Functions of melatonin
Time-keeping hormone, e.g., tells body it’s time for sleep
Establishes circadian rhythms, e.g., daily changes in body temperature, hormone and enzyme levels
Inhibits reproductive function, e.g., decreases at puberty
An antioxidant; may protect CNS neurons from free radicals
Inhibits MSH (secreted by anterior pituitary)

10. Pineal Gland
Figure 14–11a

11. Hypothalamus Location
Floor of diencephalon, below thalamus and above brainstem (mesencephalon, pons, medulla oblongata)
Extends from:
Area superior to optic chiasm (where optic nerves arrive at brain) to
Posterior margins of mamillary bodies (nuclei in floor of hypothalamus; control feeding reflexes)
Infundibulum (slender stalk) connects hypothalamus to pituitary gland
Area adjacent/posterior to infundibulum = median eminence

12. Hypothalamus
Figure 14–10a

13. 3 Endocrine Regions of Hypothalamus
Supraoptic nuclei  antidiuretic hormone (ADH)
Causes water retention at kidneys, increased blood pressure
Transported via axons of neurosecretory cells to posterior pituitary for release near fenestrated capillaries
Paraventricular nuclei  oxytocin (OT)
Stimulates smooth muscle contraction of:
Uterus, mammary glands, ductus deferens, prostate gland

14. 3 Endocrine Regions of Hypothalamus
Median eminence
Swelling near attachment of infundibulum
Where hypothalamic neurons  regulatory hormones (RHs) near fenestrated capillaries
Transported in blood to anterior pituitary via hypophyseal portal system
Stimulate/inhibit cells that produce/secrete hormones

15. Fig 18-7

16. Portal System Blood vessels that link 2 capillary networks
Capillaries  veins  capillaries  veins  heart
vs. usual pattern
Heart  arteries  capillaries in organ/tissues  veins  heart
Examples
Hepatic portal system
From GI tract to liver
Hypophyseal portal system
From hypothalamus to anterior pituitary

17. Hypophyseal Portal System
Capillaries from median eminence unite to form portal vessels (veins) that travel to anterior pituitary capillaries
RHs enter hypothalamic blood stream quickly due to fenestrated capillaries
Portal system ensures RHs reach pituitary before entering general circulation

18. Pituitary Gland (Hypophysis)
Location
In hypophyseal fossa within sella turcica of sphenoid
Connected to hypothalamus by infundibulum
Held in position by diaphragma sellae
Divided into 2 lobes/glands
Anterior pituitary (adenohypophysis)
Posterior pituitary (neurohypophysis)

19. Pituitary Gland (Hypophysis)
Figure 18–6

20. Pituitary Gland Hormones
Fig 18-9

21. Posterior Pituitary (Neurohypophysis, Pars Nervosa)
Contains axons of hypothalamic neurons (neurosecretory cells)
Releases 2 peptide hormones produced in the hypothalamus
ADH (antidiuretic hormone)
OT (oxytocin)

22. Anterior Pituitary (Adenohypophysis)
Has 3 parts (“pars”)
Pars distalis
Largest, most anterior
Produces/secretes 6 of 7 hormones (not MSH)
Pars intermedia
Narrow band bordering posterior pituitary
Produces/secretes MSH
Pars tuberalis
Wraps around infundibulum

23. Anterior Pituitary (Adenohypophysis)
Produces and releases 7 peptide hormones
ACTH (adrenocorticotropic hormone)
Stimulates production/secretion of glucocorticoids (GCs) by adrenal gland
TSH (thyroid-stimulating hormone)
Triggers secretion of thyroid hormones
GH (growth hormone)
Stimulates tissue growth
PRL (prolactin)
Stimulates mammary gland development and milk production

24. Anterior Pituitary (Adenohypophysis)
FSH (follicle-stimulating hormone)
A gonadotropin
Stimulates ovarian changes, hormone production and egg and sperm development
LH (luteinizing hormone, aka interstitial cell- stimulating hormone, ICSH)
Another gonadotropin
Triggers ovulation and corpus luteum (CL) development in females
Hormone production in both sexes
MSH (melanocyte-stimulating hormone)
Stimulates melanin production by melanocytes in stratum germinativumm of epidermis

25. Thyroid Gland Location Extensive blood supply gives it red color
Curves across anterior surface of trachea, inferior to thyroid cartilage of larynx
Extensive blood supply gives it red color
Consists of two lobes united by an isthmus
Lobes filled with thyroid follicles
Spheres formed by simple cuboidal epithelium
Cavity contains viscous colloid (proteinaceous fluid)
Surrounded by capillary network

26. Thyroid Gland
Fig 18-10a

27. Fig 18-10b

28. Thyroid Gland Hormones
Follicle cells
Simple cuboidal epithelium
 T3 and T4
Stimulate tissue metabolism, energy utilization, growth
C (clear, parafollicular) cells
 Calcitonin
Decreases serum Ca++

29. Parathyroid Glands
2 pairs of glands embedded in posterior surface of thyroid gland
Contain principal (chief) cells
 PTH (parathyroid hormone)
Increases serum Ca++

30. Parathyroid Glands
Fig 18-12a

31. Today in class we will:
Identify the following organs and tissues of the endocrine system and the locations, associated structures, hormones and the functions of those hormones secreted by each of those endocrine organs, :
Adrenal glands
Pancreas
Kidneys
Reproductive organs (gonads and placenta)
Other: heart, thymus, adipose tissue

32. Adrenal Glands aka Suprarenal glands Location 2 regions
On superior surface of kidneys
2 regions
Adrenal cortex
 steroid hormones (adrenocortical steroids/ corticosteroids)
Adrenal medulla
 epinephrine and norepinephrine (E, NE)
Under ANS control)

33. Adrenal Glands
Fig 18-14a

34. Fig 18-14b

35. Adrenal Cortex 3 Zones  Different Hormones
Fig 18-14c

36. Adrenal Cortex: 3 Zones Zona glomerulosa Zona fasciculata
Outer zone, under capsule
 mineralocorticoids, e.g., aldosterone
Zona fasciculata
Middle zone, largest region
 glucocorticoids, e.g., cortisol, cortisone
Zona reticularis
Inner zone, adjacent to medulla
 androgens, e.g., testosterone

37. Pancreas Location Appearance Has endocrine and exocrine functions
In J-shaped loop between stomach and duodenum of small intestine
Appearance
Lumpy
3 parts:
Head
Body
Tail
Has endocrine and exocrine functions

38. Pancreas
Figure 18–15

39. Endocrine Pancreas 1% of volume
Small groups of cells scattered among exocrine cells = pancreatic islets (islets of Langerhans)
Alpha cells  glucagon   blood glucose
Beta cells  insulin   blood glucose

40. Exocrine Pancreas 99% of volume
Clusters of gland cells (pancreatic acini) and ducts
Release enzyme-rich digestive juices into small intestine

41. Kidneys Location Produce hormones On either side of vertebral column
Calcitriol
Stimulates calcium and phosphate ion absorption from digestive tract
Erythropoietin (EPO)
Stimulates RBC production by bone marrow

42. Figure 26–2